This invention relates generally to turbines and, more particularly, to turbine nozzles.
Turbine nozzles are formed or configured of nozzle segments that are connected together circumferentially about an axis of a turbine engine. Each nozzle segment includes a seal slot formed at opposing side edges of the nozzle segment. A suitable seal or gasket is positioned within the seal slots of adjacent nozzle segments to form a seal to prevent or limit gas or steam from escaping the turbine engine at undesirable locations, such as between adjacent turbine nozzle segments and/or adjacent turbine nozzles. In order to maintain a proper seal, a depth and/or a width of each seal slot must be maintained within or conform to an accepted tolerance with respect to a desired engineering specification and/or dimension. Further, machined axial dimensions and/or machined radial dimensions should be inspected to ensure that such dimensions are within acceptable tolerances for the respective turbine nozzle segment. Periodic inspection of the nozzle segments, including measuring the dimensions of each seal slot, as well as the axial dimensions and/or radial dimensions of other machined features of the nozzle segment, is required to maintain proper functioning of the turbine, without performance loss.
Conventional tools and methods for measuring machined features of a turbine nozzle segment have proved to be unreliable. Frequently, inspected and/or repaired nozzles are fully assembled before it is possible to determine whether the nozzle segments are properly aligned, connected and/or sealed. Non-conforming nozzles, if installed in a turbine, may result in a subsequent performance loss of up to about 5%. Conventional tools and methods do not provide a reliable method for ensuring that individual nozzle segments conform to engineering specifications and/or dimensions.